Another 66cc wide intake porting thread

[maniac57]

This one is a wide port jug with the rectangular transfers rather than the "eyebrow" type.
Starting point intake

Exhaust

Transfers


bottom of transfers

 

[maniac57]

Getting started by knife edging bottom of transfers at case


Also smooth casting lip in top of transfers

 

[maniac57]

Also opened up entire transfer tract from top to bottom thinning the cylinder wall at the top for better flow (bigger hole)



It's hard to see from the pics, but with piston in place, the transfers are substantially bigger now with same amount of port open.
I maintained basically the same angles for the outlets but widened the flow area.
Also matching to the cases for best transfer flow.
Start

After matching

 

[maniac57]

Here are the finished transfers

 

[maniac57]

next the intake gets hogged out


About 2mm wider overall.

Exhaust gets the same but about 4mm wider overall.

 

[maniac57]

Ready for assembly


Getting a 40mm zl crank and innards from a stripped case victim.
That was ALMOST as much fun as RIDING it will be!

 

[snorks]

Looking down into the case it appears the bearings protrude into the case leaving alot of area around the bearings?
Would it be possible to stuff that area with epoxy or machined aluminium to minimise the crankcase volume?

Cheers
Simon

 

[maniac57]

Crank counterweights fill most of the open area.

 

[kevo]

Are they "40mm" intake cylinders any good for the 40mm stroke motors? I'm a new but I thought the port timing was designed for the GT5 short stroke high piston pin motors. Looks like that jug should flow real good

 

[maniac57]

No idea kevo. Have not tried fitting it to a 40mm stroke engine yet.
Should work though the compression might need a second gasket or base spacer.
There's always a way if you REALLY want it to fit....

 

[kevo]

Well how'd it work? You said a couple posts up that a zl 40mm lower was going in it.

 

[maniac57]

Edited;
The wide port jug in this thread is currently sitting like the last pic since I have too many engines waiting now...The 40mm zl rod engine already has a jug so no reason to swap yet and zl rod motor is already back together after a case swap. I simply forgot to check if this jug fit it. Sorry.